1. Field of Invention
This invention is a new device suitable for holding a door in a stationary position and prevent a door from swinging open or closed.
The device is a curved spring constructed with steel or similar compatible materials. In operation the spring is loaded by flattening the springs fabricated curve. When the spring tries to return to its original curvature, an expansive force is generated. This expansive force under the door holds the door stationary.
2. Discussion of Prior Art
Available on the market today are the following devices and methods to hold a door in a stationary position.
(A) Triangular Shaped Devices;
This is the most common device to hold a door stationary. The bottom of the door is forced onto a triangular shaped device or shim. This action twists and lifts the door whereby the weight and torque of the door compresses the shim. This compression force is transferred through the shim and onto the floor. The vertical force generated by the door and the friction between the door to shim and shim to floor prevents the door from swinging.
The disadvantages of triangular shim devices are:
(a) A triangular shim device is unidirectional. This is because a triangular shim can only prevent a door from swinging in one direction but free to move in the opposite direction. Also a triangular shim can only be engaged from one side of a door's swing since the door must be pulled up the slope of the shim.
(b) The shim material may relax under load, losing its expansive force and allows the door to move.
(c) The holding force on the door is determined by the initial loading of the door onto the shim. A stronger person will impose a larger holding force for the door than a weaker person.
(B) Magnetic Devices and Hooks:
These require exact alignment of the door to the magnet or hook to work. Also a door can only be opened to a predetermined position. This may not always be desirable.
(C) Heavy Objects:
A heavy object such as a chair or a brick is used to block a door open. This method is not desirable because the object restricts a doorway's clearance.
(D) Many devices have also been proposed in prior patents including U.S. Pat. No. 4,976,479 (Lunn). This discloses a spring arrangement covered by a rubber frictional coating which provides a base plate for resting on the floor and a spring plate at an angle to the base plate to form a spring wedge.